At any craft store, purchase enough Popsicle sticks (or other small wooden planks) to spell out 3-4 numbers for a password to be used in your room. 

To prepare your sticks, lay them out on the table in the password, such as 079.

Place corresponding dots or other shapes where there will be matches so the group can place them together. Be sure that each match is unique (see below). 

 

Once the dots are dry, jumble up your sticks and place them anywhere in the room. Keep them together or scatter them and have the group find all the pieces.  They should figure out that the codes match and instruct them how to put them together.   When they are placed together with the corresponding patterns (dots), they'll spell out the code they need for something in the room - maybe a combination lock, password to a USB, password to a computer, iPad, etc.